Modern processing operations for preparing chicken, beef, pork, veal, turkey, duck, or other meats typically include an automated system that generally comprises slaughtering, bleeding, scalding, evisceration, cleaning, chilling, and packaging steps. Each step normally requires careful control to prevent cross-contamination, prevent spoilage, and possibly illness from subsequent consumption. Due to its very nature, the process of evisceration exposes the exterior body surfaces and inner body cavities of the animals or birds to the contents of digestive and intestinal tracts. As a result, the evisceration process can cause excrement, blood clots, or other pathogen-laden particulate matter to deposit and become attached to the carcass. Consequently, immediately after the evisceration step, levels of bacteria and other pathogens on the surface of the carcass typically increase relative to pre-evisceration levels.
Several methods have been developed to reduce the overall contamination rate post evisceration. Among these are co-current and counter-current chill tank systems and the addition of various processing aids to these tanks. Sonification may also be employed in chill tanks at sonic or ultrasonic frequencies.
Other methods include mechanically spraying the carcass with water and/or a treatment solution, possibly including the use of such fluids under high pressure. Additional methods include contacting the eviscerated carcass with a treatment solution in a rotating drum or immersion in a drag-through dip tank.
The use of chlorine in various forms, and the use of chlorine dioxide gas in particular as a sterilizing or sanitizing agent have long been known. One reason that chlorine-based solutions are not widely used in sterilization and sanitation systems is the problem of outgassing of hazardous chemicals from chlorine dioxide solutions. For example, current OSHA regulations permit a maximum exposure level to chlorine dioxide of under 0.1 ppm. This is a significantly lower concentration than is required for its efficacy as an anti-microbial agent. Maximum exposure levels also exist for other types of sterilizing or sanitizing agents that could otherwise be used in the food processing industry.